1. Field of the Invention
The present invention relates to a method and system for removing outdated files from a network system and, in particular, removing outdated print files from a network printing system.
2. Description of the Related Art
Network printing systems generally comprise an assemblage of different printers, client computers, servers, and other components connected over a network. A print job is assembled at a client computer and transmitted over the network to a server linked to a variety of printers. The printers may have different printing capabilities. Thus, for a given submitted print job, some printers in the network may not be able to process the print job. To route print jobs through a network printing system, International Business Machines Corporation (IBM) provides Printing Systems Manager (PSM) products that provide centralized and distributed management of a network printing system. The IBM PSM systems manage the flow of print jobs and insure that a print job is routed to a printer that can handle the job.
A print job is comprised of one or more electronically-stored files and the print attributes therefor. The print attributes inform the printer how to process the files. To assemble print jobs, previous systems include software installed on the client computer that displays a graphical user interface (GUI). Using a mouse, keyboard, etc., the user selects from a menu of options displayed in the GUI the components and print attributes for a print job. The client computer, under control of the installed software, would then create an electronically-stored job ticket based on the information entered by the user or systems operator.
Job tickets typically only define the print attributes for a single file. However, a document may be comprised of multiple files, each having on or more print attributes. A file submitted to the printer often includes printer instructions in a page description language (PDL) such as POSTSCRIPT(trademark). POSTSCRIPT is a trademark of Adobe Systems, Incorporated. The PostScript language is used by many printers and applications to provide the complex fonts, graphics, and image handling capabilities required by today""s applications. The PostScript language must be interpreted by a transform process in the printer or elsewhere in the network to produce a printed image file that is ready to be printed. Print image files are in a bit-mapped image format, also known as a raster image. A raster image processor (RIP) translates PDL files to a raster image or RIP version of the file. In the desktop publishing environment, it can take several hours to transform a large PDL print file to its RIP version.
The IBM AIX(copyright) PRINT SERVICES FACILITY(trademark)/6000 (PSF/6000) software system transforms PostScript files into an Advanced Function Presentation data stream (AFP data stream) for printing on printers attached to a machine implementing the PSF/6000 software. AIX is a registered trademark of IBM and PRINT SERVICES FACILITY is a trademark of IBM. The PSF/6000 software uses the PS2AFP transform command to transform PostScript and other file formats into an AFP data stream file without submitting it immediately to the printer. The PS2AFP command runs as a daemon, which is a program that runs unattended in the background of the operating system. Daemon processes generally provide services that must be available at all times. A daemon runs continuously, looking for work to do, performing that work, and waiting for more work.
In previous systems, including those that implement the ISO DPA 10175, POSIX 1387.4 and PSIS printing standards, such as the IBM Printer Resource Manager products, print jobs are received and queued at a single point before being routed to a logical printer or printer that can handle the print job. Such a single point queue is sometimes referred to as a xe2x80x9cspooler.xe2x80x9d Spoolers are servers that accept requests from many clients, validate job and document attributes with those of the intended print destination, provide queuing and scheduling, and then route jobs/documents to the appropriate printer. A queued print job is then transferred to a logical printer, which then routes the print job to a queue for one or more physical printers.
One problem with present network printing systems is that print job files are typically resent from a printer manager to a downstream component for printing each time the print job is submitted. In network systems with numerous multiple printers and servers, network traffic can substantially increase and bottlenecks can form if large files or print jobs are continually resent through the system whenever the print job is submitted. There is, thus, a need in the art for an improved method and system for handling large print jobs or files in a network system.
To overcome the limitations in the prior art described above, preferred embodiments disclose a system and method for managing files in a network system. A processing unit detects an update to a file maintained in a storage unit. At least one network device maintains a copy of the file to update that is a previous version of the file to update maintained at the storage unit. The processing unit processes a data structure indicating network devices that include previous versions of the file and determines the network devices that include at least one previous version of the file. The processing unit then transmits a message to the network devices that include at least one previous version of the file to delete the previous versions of the file.
In further embodiments the file to update is a print file and the print file is a component of a print job. The network devices include printer controllers to process the print file. The data structure indicating network devices that include previous versions of the print file is a first data structure. Further, the processing unit, when determining the network devices that include the previous versions of the print file, processes a second data structure indicating print jobs and the component print files of the print jobs to determine print jobs including the previous version of the print file.
In current network printing systems, print files are often not maintained at distributed network devices, such as controllers and printers, to allow for reuse of the print files. Reuse reduces network traffic because the same print job does not have to be repeatedly transmitted from a central repository to a controller or printer. With reuse, a copy of the print job may be maintained at distributed controllers or printers, thereby obviating the need to continually provide the controller or printer with a copy of the file to RIP or print. However, if multiple copies of a file are maintained throughout the network, the updating of the file at a central repository location would outdate the other copies of the files distributed throughout the network system. Preferred embodiments provide a system and method for insuring that outdated files are not maintained at distributed network devices, such as printers or controllers. With preferred embodiments, after an update to a file is made, the outdated copies of the file are removed from the network devices that maintain such copy. This insures that outdated versions of the file will not be processed, printed or otherwise used in the network system. Moreover, with preferred embodiments, any request to process a file within the network system that is the subject of a clean-up request is not executed or is otherwise suspended until outdated versions of that file have been removed (cleaned) from devices within the network system.